有没有更简单的方法可以使用FlatBuffers序列化[] [] byte？

Question

I am looking to serialize a [][]byte message with FlatBuffers. Given than FBS Vectors cannot be nested it seems that this is the way to go:

namespace msgfbs;

table SubmitMessage {
  nonces:[Nonce];
}

table Nonce {
  bytes:[ubyte];
}

Now to write this structure I ended up writing this function:

func NewSubmitMessage(builder *fbs.Builder, nonces [][]byte) []byte {
    builder.Reset()

    nonceCount := len(nonces)

    // Convert nonces to byte vectors
    byteVectors := make([]fbs.UOffsetT, nonceCount)
    for i, nonce := range nonces {
        byteVectors[i] = builder.CreateByteVector(nonce)
    }

    // Create FBS Nonces
    noncesFbs := make([]fbs.UOffsetT, nonceCount)
    for i := range nonces {
        msgfbs.NonceStart(builder)
        msgfbs.NonceAddBytes(builder, byteVectors[i])
        noncesFbs[i] = msgfbs.NonceEnd(builder)
    }

    // Create vector of FBS Nonces
    msgfbs.SubmitMessageStartNoncesVector(builder, nonceCount)
    for i := nonceCount - 1; i >= 0; i-- {
        builder.PrependUOffsetT(noncesFbs[i])
    }
    noncesVector := builder.EndVector(nonceCount)

    // Create message
    msgfbs.SubmitMessageStart(builder)
    msgfbs.SubmitMessageAddNonces(builder, noncesVector)
    builder.Finish(msgfbs.SubmitMessageEnd(builder))
    builder.PrependByte(Submit)

    return builder.FinishedBytes()
}

I need 3 consecutive for-loop before finally wrapping up my message. Is this the simplest way to serialize a [][]byte? Is there a more efficient way to achieve the same?

Answer 1

The first 2 for loops can be merged: you can create the byte vector, followed by the table holding it. You just can't nest the byte vector between Start/End.

For the last for loop there really should be a helper function doing this for you (they exist for other languages). If there's none in Go, create an issue (or better yet, a PR) on the FlatBuffers repo.